Three students measured the weight of a ball, their results were: John: 24.3 ± 0.1 g
Mark: 24.3 ± 0.2 g
Peter: 24.3 ± 0.3 g

The most precise student was:

Atomic nuclei of almost all elements consist of

I'm thinking it's 2 you are asked to explain the earth's magnetic field. which is the best reply? 1. the earth's magnetic south is similar to the north pole of a magnet. 2. the earth's core has a strong magnetic charge similar to the south pole of a magnet. 3. the earth's geomagnetic south is similar to the south pole of a magnet. 4. the earth's magnetic charge is not centered at either pole; it varies based on location.

How to tell if two objects are in thermal equilibrium 1.the objects have the same temperature 2.the objects are the same size 3.the objects are touching each other 4.the objects temperatures are changing